So, I’ve had the car for a while and recently the cars been struggling to start after being driven hard, I took it to a garage and he replaced the timing belt because it was very very loose, didn’t skip tho. I just wondered what it could be. So when it’s warm it’ll struggle to start unless I fully turn and hold the key for about 5 seconds and then it idles and runs fine the rest of the time 

4 hours ago, Rowan432 said:

when it’s warm it’ll struggle to start

Warm or hot? I've got a possible idea, but it's dependent on engine temperature.

I had this problem on an Ibiza Cupra Tdi. It was either a camshaft sensor or the injector seals…. We replaced both and the problem was solved… It struggled to start once at operating temp and turned off…. It would start really hard and the engine would throw itself about the engine bay violently, I was thinking it was gonna destroy all the engine mounts…. Horrible!

Mine was doing this, after I changed loads of other things the auto electrician found some broken wires under the 'battery area' I didn't fix it myself so can't confirm exact location but it's been sound ever since.